Background/Aims: While obsessive-compulsive disorder (OCD) is specifically characterised by compulsivity, considerable literature suggests impulsivity also plays an important role in the disorder. However, impulsivity is a multi-faceted construct and the exact relationship of trait impulsivity to OCD remains unclear. Therefore, this scoping review aimed to collate and review studies of trait impulsivity in OCD by an investigation of: 1. How trait impulsivity in OCD is measured in the research literature; 2. How people with OCD perform on these measures and compare to healthy and other psychiatric groups; and 3. What correlations with trait impulsivity are observed in OCD. Methods: This study was pre-registered on PROSPERO (CRD42023481781). Electronic search of PubMed, Scopus, and PsycINFO databases using keywords '(impuls*) AND (OCD)' was undertaken without date restrictions for peer-reviewed articles available in English. After exclusion of duplicates and screening of 1476 abstracts, 114 articles were identified for full-text review. Results: 54 articles were reviewed after excluding studies assessing neurocognitive impulsivity only (i.e. no inclusion of trait impulsivity), sub-clinical OCD symptoms, and review articles. The literature reports cross-sectional clinician-rated and self-rated trait impulsivity data, with the Barratt Impulsivity Scale (BIS) being used most frequently. Broadly, people with OCD scored higher than healthy controls on at least one aspect of trait impulsivity. However, comparisons of OCD groups to other psychiatric groups demonstrated equal or lower trait impulsivity in OCD. Individuals with OCD with comorbid diagnoses (ADHD, behavioural addictions, tic disorder, borderline personality disorder, bipolar disorder) had relatively higher levels of trait impulsivity than those without. In OCD, trait impulsivity scores were associated with various psychiatric symptomatology (OCD severity, anxiety, depression, compulsivity, hoarding levels, behavioural addictions, anhedonia, aggressive and sexual impulses). Trait impulsivity did not correlate with neurocognitive measures of impulsivity. Conclusions: Key findings are that trait impulsivity research in OCD was predominantly observational, with cross-sectional studies using the BIS. While higher levels of trait impulsivity were seen in patients with OCD compared to healthy controls, this finding was not specific to OCD. OCD demonstrated equal or lower trait impulsivity than other psychiatric groups that the literature had examined to date; trait impulsivity in OCD was positively correlated with a number of psychiatric factors; and neurocognitive measures of impulsivity did not correlate with trait impulsivity. Future work on OCD should include interventional and neuroimaging methods that utilise several different measures of impulsivity. Keywords: Obsessive-compulsive disorder; OCD; impulsivity; trait impulsivity
